In a driving cycle of a motor vehicle, an considerable portion of the hydrocarbon emissions is generated during the warm-up of the internal combustion engine. One of the reasons for that is that the catalytic converter in an exhaust system of the motor vehicle is not sufficiently converted at the beginning of the warm-up so that the emissions are not cleaned or cleaned only insufficiently by the catalytic converter during the warm-up. For this reason, optimizing the warm-up is of interest. For this purpose, operating parameters may be controlled during the warm-up, assuming, however, that the operating parameters to be controlled may be measured.
In this context, a method for checking an air mass sensor for an internal combustion engine is discussed in the publication DE 10 2007 013 460 A1. A cylinder pressure is determined in this case and used for ascertaining an indicated mean effective pressure. The indicated mean effective pressure is used together with a thermal efficiency to determine a fuel quantity to be injected. Furthermore, the oxygen quantity and the air mass are determined at least in a stationary case from a lambda value, which describes an oxygen/fuel quantity ratio, and from the fuel quantity, and the determined air mass is compared to an air mass measured by an air mass sensor.